PVDF螺旋卷式膜组件制备及真空膜蒸馏性能研究

真空膜蒸馏工艺作为一种具有良好应用前景的膜蒸馏操作方式得到了广泛的研究.当前常用于真空膜蒸馏研究的膜组件包括平板式、管式和中空纤维式.尝试制备了一种用于真空膜蒸馏的螺旋卷式膜组件,通过试验对自制组件的性能进行了研究,证实了卷式膜组件真空膜蒸馏操作的可行性.在真空度为-0.092 MPa,温度为67.7℃的操作条件下,得到了10.43 kg/(m2·h)的通量.通过试验比较了所制备卷式膜的通量与膜材料本底通量的差别,并对所存在的问题进行了分析.     

真空技术在化学工业中的应用

真空技术广泛的应用于化学工业生产之中,所使用的真空度范围很宽,从几十毫米 汞柱到万分之几的毫米汞柱真空度,视被处理物料的性质和工艺要求而异,应用真空技 术,大致可分为如下几个方面: 1.在化工生产流程中,真空蒸馏、真空蒸发、真空干燥等单元用途较广。基本原理 是在真空下,使被处理物料的某些组份沸点降低,能够在较低温度下操作。这样,一方 面可以避免热敏性物料在较高温度时破坏;另一方面因为可以用较低温度的热源加热, 在生产中易于解决;再则是在真空下操作,降低系统中氧的含量,可以免除物料的氧化 变质。 例如蒸馏苯酚,苯酚的沸点是…     

太阳能自动跟踪膜蒸馏系统实验研究

搭建设计了太阳能自动跟踪膜蒸馏系统,自制配比苦咸水,在不同膜蒸馏方式下观测膜蒸馏对离子的截留效果,研究了流体温度、流量、真空度以及并联膜组件对真空膜蒸馏过程性能的影响.其次,在不同跟踪方式下对集热器换热性能进行测试,并研究了太阳辐照量对光伏组件的影响.最后,对系统性能随太阳辐照度的变化进行了测试分析.结果表明,膜蒸馏截留率均保持在97%以上;膜通量随温度、真空度的增大而增大,流量对膜通量影响较小;并联膜组件产水量是单支膜组件产水量的2倍.真空集热器与保温水箱的最佳循环流量200 L/h;自动跟踪方式集热量较大;光伏组件的输出功率与太阳辐照度成正比.采用真空式膜蒸馏在自动跟踪方式下,当太阳能集热器面积为1.82 m²,光伏板面积为6.5 m²时,最大膜通量为7.70 kg/(m²·h),膜蒸馏产水量最大为462.27 g/h.     

真空干燥动力学实验平台的设计及测试北大核心CSCD

真空干燥既能保证干燥后物料品质,又能提高干燥速率,且具有干燥温度低,温差热应力小和适用于热敏性物料干燥等优点。相对于传统热风干燥,作为热敏性作物的稻谷采用真空干燥可以有效降低爆腰率和提高发芽率。为研究稻谷真空干燥动力学特性,设计搭建了可准确控制相对压力、温度并实时测量质量的干燥动力学实验平台。该平台包括真空控制模块、温度控制模块、质量称量模块、实时数据采集与控制模块以及数据处理模块。对实验平台的真空控制、温度控制和质量测量性能进行测试分析,结果表明该平台能够实现相对压力和温度的准确控制并实现干燥数据的实时精确采集。     

真空干燥动力学实验平台的设计及测试

真空干燥既能保证干燥后物料品质,又能提高干燥速率,且具有干燥温度低,温差热应力小和适用于热敏性物料干燥等优点。相对于传统热风干燥,作为热敏性作物的稻谷采用真空干燥可以有效降低爆腰率和提高发芽率。为研究稻谷真空干燥动力学特性,设计搭建了可准确控制相对压力、温度并实时测量质量的干燥动力学实验平台。该平台包括真空控制模块、温度控制模块、质量称量模块、实时数据采集与控制模块以及数据处理模块。对实验平台的真空控制、温度控制和质量测量性能进行测试分析,结果表明该平台能够实现相对压力和温度的准确控制并实现干燥数据的实时精确采集。     

PVDF中空纤维膜组件特性参数对淡化浓盐水VMD性能的影响

研究聚偏氟乙烯中空纤维膜组件性能参数(高径比、装填封率)对淡化浓盐水真空膜蒸馏(VMD)性能的影响,获得适用于淡化浓盐水VMD过程膜组件制备的优化参数.小试实验研究了膜组件高径比为分别为25∶2、15∶1、35∶2、20∶1、45∶2及装填封率分别为1%、5%、10%条件下的淡化浓盐水真空膜蒸馏性能.在真空膜蒸馏中试试验中,研究膜组件高径比分别为10∶3、70∶9、10∶1,装填封率分别为7.11%、9.48%、14.22%条件下的膜蒸馏性能.结果表明,在同等条件下高径比或装填封率越小时,膜蒸馏的渗透通量越大.淡化浓盐水VMD过程产品水脱盐率均在99.9%以上.     

海水淡化浓盐水真空膜蒸馏研究

采用PVDF中空纤维膜及PTFE微孔平板膜组件对反渗透海水淡化浓盐水的真空膜蒸馏过程进行了研究.连续运行的结果表明:温度是影响海水淡化浓盐水膜蒸馏过程的关键因素,对膜通量影响较大.在真空侧压力为2 kPa,浓盐水流量为24 L/h时,进料侧浓盐水温度为346.35 K时,PVDF中空纤维膜组件的膜蒸馏通量为13.26 kg/(m2.h).而在真空侧压力为2 kPa,浓盐水流量为120 L/h,进料侧浓盐水温度为340.15 K时,PTFE平板膜组件的膜蒸馏通量为24.8 kg/(m2.h).研究表明膜蒸馏技术处理海水淡化浓盐水具有广阔的应用前景.     

膜蒸馏系统的热质扩散耦合分析

从相变耦合、逆流换热耦合以及蒸汽分子在膜孔中热质扩散耦合的角度出发,分别分析了热物料侧相变热质传递过程、膜蒸馏系统逆流换热过程以及蒸汽分子在膜孔中的热质扩散过程,并建立了三者与膜通量之间的关系式.得出自发的蒸汽分子迁移过程驱动了非自发的传热过程,当传质过程强化时,蒸汽分子传递速率增加,导致膜通量增加;膜蒸馏系统换热的强化有助于削弱温度极化,伴随着膜两侧表面温度梯度的增加,膜通量增加;关系式同时说明了减小膜的厚度,有利于膜通量增加.     

真空干燥箱内温度分布特征研究

真空干燥箱可在常温甚至低温下干燥物料,特别适用于热敏性、易分解、易氧化等物品的快速干燥,在食品加工、医药制药等行业得到广泛应用。文章采用经校准的无线温度记录仪测量了真空干燥箱在常压和1 kPa两种工作条件下,工作区域温度分布特点,研究结果表明此两种条件下,真空干燥箱内温度波动度均小于1℃;由于传热方式的改变,1 kPa条件下温场均匀性变差。     

新型膜蒸馏组件中半导体制冷性能试验研究

提出一种具有半导体制冷的新型膜蒸馏组件,基于半导体制冷原理,选择最佳散热方式——水冷散热,试验研究在同种条件下静态和扰动水域的变化对半导体制冷组件性能的影响。研究结果表明：散热水域的温度以及搅动对其制冷性能影响较大,半导体制冷组件在一定工况运行时,制冷表面温度稳定,保持在-3.2℃,可以满足膜蒸馏进行所需的冷端条件,证明半导体制冷组件可以与膜蒸馏过程耦合,为半导体制冷组件在膜蒸馏试验中的应用提供试验依据。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.